# Spatial variations of the SrI 4607\AA scattering polarization signals at subgranular scale observed with ZIMPOL at GREGOR telescope

## TL;DR

This study measures the spatial variations of scattering polarization signals in the Sr I 4607Å line at granular scales on the Sun, revealing higher polarization in granular regions using high-resolution spectropolarimetry.

## Contribution

First high-resolution spectropolarimetric measurements of Sr I 4607Å scattering polarization at subgranular scales with ZIMPOL at GREGOR.

## Key findings

- Polarization signals vary at granular scales across different limb distances.
- Higher polarization amplitudes are statistically associated with granular regions.
- Spatial variations of polarization are observed consistently at all examined limb distances.

## Abstract

Sr I 4607\AA spectral line shows one of the strongest scattering polarization signals in the visible solar spectrum. The amplitudes of these signals are expected to vary at granular spatial scales. This variation can be due to changes in the magnetic field intensity and orientation (Hanle effect) as well as due to spatial and temporal variations in the plasma properties. Measuring the spatial variation of such polarization signal would allow us to study the properties of the magnetic fields at subgranular region. But, the observations are challenging since both high spatial resolution and high spectropolarimetric sensitivity are required at the same time. To the aim of measuring these spatial variations at granular scale, we carried out a spectro-polarimetric measurement with the Zurich IMaging POLarimeter (ZIMPOL), at the GREGOR solar telescope at different limb distances on solar disk. Our results show a spatial variation of scattering linear polarization signals in Sr I 4607\AA line at the granular scale at every $\mu$, starting from 0.2 to 0.8. The correlation between the polarization signal amplitude and the continuum intensity imply statistically that the scattering polarization is higher at the granular regions than in the intergranular lanes.